Child safety seats of motor vehicles are well known. They normally comprise either a rear facing seat in which the infant's back is facing the direction of travel of the motor vehicle, or a forward facing seat. The rear facing seat is normally used for infants up to the age of six months, and the forward facing seat is used for infants older than six months.
Both the rear and forward facing seats make use of a tether strap that extends from the head end of the seat to an attachment point that is fixed with respect to the vehicle. This might comprise a parcel shelf, floor panel behind the seat, or a side pillar.
In case of a rear facing seat, it is normal for a pair of straps to extend from either side of the head end of the seat to the rear connection point. However, in the case of a forward facing seat, it is normal for a single strap to be used and the strap extends from the centre of the head end of the seat to the attachment point.
One difficulty with the use of a single strap is the need to have a number of components in line with the strap. These components comprise a length adjusting means, a hook, and a means of attaching the strap to the hook. The use of all of these components adds length to the tether strap, and therefore means that the strap will still be reasonably long even though it is adjusted to its shortest possible length. In some instances, this length is too long for use with the most convenient attachment point in the vehicle.
It is now common for a single support seat to be adapted for use in both the rear and forward facing modes. To date, most of such dual purpose seats have made use of two tether straps, one for when the seat is in a rear facing mode, and one for when the seat is in a forward facing mode. This represents an unnecessary added cost, and also presents the possibility of incorrect installation when the wrong tether strap is used.